Re: limit for number of objects in notifications

[Wes Hardaker <wes@hardakers.net>]

>>>>> On Tue, 28 Dec 2004 11:26:42 +0100, Juergen Schoenwaelder <j.schoenwaelder@iu-bremen.de> said:

Juergen> The engineIDs are restricted in MIB space to (SIZE(5..32)) and the
Juergen> context name is restricted in the VACM MIB to (SIZE(0..32)). With
Juergen> AES/DES and USM, the msgPrivacyParameters contains an 8 octet
Juergen> value.

Also remember that with DES you get potential padding at the end of
original scoped pud within the encrypted message.  This will be
between 0 to 7 bytes of extra (bogus) data.  AES, due to the use of
CFB mode, doesn't require this.

(It's actually not DES that requires it, its the use of CBC mode that
does.  If AES had used CBC mode instead of CFB mode, it too would
require padding).

Juergen> Assuming an empty context name and values in the middle of
Juergen> the ranges, it should be possible to calculate the likely
Juergen> size of an SNMPv3 header.

The usm user name is not likely to be in the middle of the range.
It's likely to be closer to the front.  I'd bet the average user name
length would be at most 8 (average, not max).  Probably less.

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